Read file and parse each row

Hoxygen232 · 08-23-2015, 06:03 AM

Hi,

I have a file that contains rows like these:

Code:

128.199.248.105:54
217.12.210.54:54
77.66.84.233:443
77.66.84.233:5353
176.56.237.171:443

I need to read that file and for each row run this command:

Code:

dig google.com @ADDRESS -p PORT

in this case:

Code:

dig google.com @128.199.248.105 -p 54
dig google.com @217.12.210.54 -p 54
dig google.com @77.66.84.233 -p 443
dig google.com @77.66.84.233 -p 5353
dig google.com @176.56.237.171 -p 443

How can I do that?

Thanks

wpeckham · 08-23-2015, 06:10 AM

First, is this some kind of education assignment?
Second, what have you tried or considered so far?
Third, what are your tools? Is your use constrained to a certain shell, interpreter, or environment?

AnanthaP · 08-23-2015, 06:15 AM

Since you have a file all you need to do is:
(1) Insert dig google.com @ at the beginning of each line,
(2) Replace all occurrences of the colon (

character with a space followed by a -p followed by a space

You now have a script file.

Make it executable and execute the script.

OK

Hoxygen232 · 08-23-2015, 06:23 AM

It's a script I'm writing for myself.
I'm using bash.
I tried to pul all addresses (substring that end with ":" character) in an array, but I don't how to extract the PORT and use it in the command.

HMW · 08-23-2015, 06:27 AM

Quote:

Originally Posted by AnanthaP

Since you have a file all you need to do is:
(1) Insert dig google.com @ at the beginning of each line,
(2) Replace all occurrences of the colon (

character with a space followed by a -p followed by a space

You now have a script file.

Make it executable and execute the script.

OK

^This will pretty much do it. But the ports can be an issue. How would you decide which port to use for which line (ip address) in the script?

Best,
HMW

Edit: Forget this part: How would you decide which port to use for which line (ip address) in the script? I didn't read the first post properly!!!

grail · 08-23-2015, 06:39 AM

Look up a while / read loop and what setting IFS might do for you. With just a little searching I am sure you could this trivially.

syg00 · 08-23-2015, 06:49 AM

Quote:

Originally Posted by Hoxygen232

I tried to pul all addresses (substring that end with ":" character) in an array, but I don't how to extract the PORT and use it in the command.

Better perhaps to use sed - easy enough to separate the bits you want to keep and use, and replace the bits you don't.

Hoxygen232 · 08-23-2015, 09:04 AM

I'll try thanks

wpeckham · 08-24-2015, 05:38 AM

Assuming your source file name is source.txt
and you want the results in my.script,
you might try something like this:

Code:

for foo in `cat source.txt` ; do
   IP=`echo ${foo}|cut -d: -f1`
   PORT=`echo ${foo}|cut -d: -f2`
   echo "dig google @${IP} -p ${PORT}"
done > my.script

Naturally, there are almost unlimited ways to do this depending upon what tools you want to use.
Bash string manipulation could easily pull apart the strings into IP and PORT without calling cut, but cut is clear and easy to understand, and performance is not really at issue with so small a file. The sed and awk utilities COULD be used, and perl would make it easy, but bash has everything you really need.

HMW · 08-24-2015, 05:40 AM

Quote:

Originally Posted by grail

Look up a while / read loop and what setting IFS might do for you. With just a little searching I am sure you could this trivially.

I had to try this approach, and I agree that using a while loop and setting IFS appropriately is probably the smoothest way to go. Three lines of code and you're done!

My output (with echo instead of an actual "dig" at Google!):

Code:

dig google.com @128.199.248.105 -p 54
dig google.com @217.12.210.54 -p 54
dig google.com @77.66.84.233 -p 443
dig google.com @77.66.84.233 -p 5353
dig google.com @176.56.237.171 -p 443

Best regards,
HMW